<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js webgl - instancing - raycast</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">
	</head>
	<body>
		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			import Stats from 'three/addons/libs/stats.module.js';
			import { GUI } from 'three/addons/libs/lil-gui.module.min.js';
			import { OrbitControls } from 'three/addons/controls/OrbitControls.js';

			let camera, scene, renderer, controls, stats;

			let mesh;
			const amount = parseInt( window.location.search.slice( 1 ) ) || 10;
			const count = Math.pow( amount, 3 );

			const raycaster = new THREE.Raycaster();
			const mouse = new THREE.Vector2( 1, 1 );

			const color = new THREE.Color();
			const white = new THREE.Color().setHex( 0xffffff );

			init();

			function init() {

				camera = new THREE.PerspectiveCamera( 60, window.innerWidth / window.innerHeight, 0.1, 100 );
				camera.position.set( amount, amount, amount );
				camera.lookAt( 0, 0, 0 );

				scene = new THREE.Scene();

				const light = new THREE.HemisphereLight( 0xffffff, 0x888888, 3 );
				light.position.set( 0, 1, 0 );
				scene.add( light );

				const geometry = new THREE.IcosahedronGeometry( 0.5, 3 );
				const material = new THREE.MeshPhongMaterial( { color: 0xffffff } );

				mesh = new THREE.InstancedMesh( geometry, material, count );

				let i = 0;
				const offset = ( amount - 1 ) / 2;

				const matrix = new THREE.Matrix4();

				for ( let x = 0; x < amount; x ++ ) {

					for ( let y = 0; y < amount; y ++ ) {

						for ( let z = 0; z < amount; z ++ ) {

							matrix.setPosition( offset - x, offset - y, offset - z );

							mesh.setMatrixAt( i, matrix );
							mesh.setColorAt( i, color );

							i ++;

						}

					}

				}

				scene.add( mesh );

				//

				const gui = new GUI();
				gui.add( mesh, 'count', 0, count );

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( animate );
				document.body.appendChild( renderer.domElement );

				controls = new OrbitControls( camera, renderer.domElement );
				controls.enableDamping = true;
				controls.enableZoom = false;
				controls.enablePan = false;

				stats = new Stats();
				document.body.appendChild( stats.dom );

				window.addEventListener( 'resize', onWindowResize );
				document.addEventListener( 'mousemove', onMouseMove );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			function onMouseMove( event ) {

				event.preventDefault();

				mouse.x = ( event.clientX / window.innerWidth ) * 2 - 1;
				mouse.y = - ( event.clientY / window.innerHeight ) * 2 + 1;

			}

			function animate() {

				controls.update();

				raycaster.setFromCamera( mouse, camera );

				const intersection = raycaster.intersectObject( mesh );

				if ( intersection.length > 0 ) {

					const instanceId = intersection[ 0 ].instanceId;

					mesh.getColorAt( instanceId, color );

					if ( color.equals( white ) ) {

						mesh.setColorAt( instanceId, color.setHex( Math.random() * 0xffffff ) );

						mesh.instanceColor.needsUpdate = true;

					}

				}

				renderer.render( scene, camera );

				stats.update();

			}

		</script>
	</body>
</html>
